The present invention relates to a storage electrode of a DRAM cell in a highly-integrated semiconductor device and the manufacturing method therefor, and more particularly to a storage electrode having a plurality of bars consisting of conductive material between upper and lower plates thereof in order to enlarge the surface area of the storage electrode, and a method for manufacturing the same.
As the semiconductor devices become highly integrated, an area occupied by a capacitor of a DRAM cell shrinks, which in turn decreases the capacity of the capacitor. Therefore, a continuous effort has been made for developing a storage electrode whose surface area is enlarged to increase the capacity of the capacitor, while minimizing the per unit mean area occupied by the capacitor thereof. A tunnel-type storage electrode which is one example showing such an effort, and will be illustrated with reference to FIG. 1.
FIG. 1 is a sectional view showing the tunnel-type storage electrode of a DRAM cell manufactured by a conventional technique. Here, a field oxide layer 2 is formed on a predetermined portion of a silicon substrate 1, and a MOSFET(not shown) having a source, a drain and a gate electrode is formed on a predetermined portion of the silicon substrate 1. (A reference numeral 3 designates a drain diffusion region.) A first insulating layer 4 is formed on the entire surface of the structure in such a manner that a contact hole 5 is provided for the purpose of exposing the drain diffusion region 3, and a first conductive layer 6 for storage electrode comes in contact with the drain diffusion region 3. Then, a second conductive layer 8 for storage electrode having a space shaped as a tunnel, is formed thereon, thereby completing the tunnel-type storage electrode 10.
However, in spite of forming the storage electrode in the shape of tunnel, there is a limitation in enlarging the surface area of the storage electrode when the packing density is further increased. Nevertheless, in order to increase the surface area of the storage electrode, the tunnel height within the storage electrode must be increased, thus making the succeeding process difficult due to high steps generated by the storage electrode.